You can't compare post WWII 35mm images to smaller format (inc 35mm) pre-WWII images. Photography had changed in so many ways, and you can add some dates to this timeline.
New optical glasses from Zeiss Abbe around 1924 allowing new fast lenses to be produce, like the f1.8 Ermanox, the Meyer f1.5 Plasmat, etc, but plate/film emulsions were not particularly fine grained, or sharp, so enlargement had to be small.
The major improvements in film came in 1934 with the first generation of modern films (plates) Ilford Selochrome Fine Grain Panchromatic, and Hypersensitive Panchromatic, Agfa would have had something similar. Ilord upgraded to FP2 and HP2 in 1937. Kodak lagged behind only introducing their equivalents in 1939 Plus-X Super-XX, & Tri-X, the latter only available as sheet film.
Ilford FP3 & HP3 followed quite quickly, FP3 &HP3 plates in 1942, HP3 film 1943, FP3 film in 1946. The other huge improvement was lens coating introduced by Zeiss in 1938, although only a few pre-WWII Zeiss lenses were coated. Here in the UK Taylor, Taylor, & Hobson had perfected lens coatings slightly earlier but it was deemed to be a military secret by the Government. Post WWII almost all lenses were coated.
There are tw other factors, first the introduction of small accurate light meters, which allowed for the second a change in development technique,.To minimise grain with 35mm you need to exose accurately and develop optimally to match the printing paper. The older techicque of over exposure and longer development often in Pyro developer, or quite vigourous MQ devlopers increases grain size.
Hans Windisch wrote about the new approach in his seminal book Die Neu Foto Schule/The New Photo School, updated afer WWII as The Manual of Modern Photography, The Technique. It is the way we essentially all work today.
Ian